The purpose of this study is to maintain high efficiency and reasonable use of cool thermal storage systems operated in the domestic building sector. As the result of efficiency test from the five types of operated cool storage systems on the condition that COP ranges are 2.6 to 3.4 during the day time and 2.1 to 3.0 during the night time and it decreased by more than 30% of rated COP given 3.8 to 3.0. The Analysis of cool storage rate shows that only 3 (21.4%) systems out of 15 buildings hold to over 40% capacity for its total capacity. To prevent the decrease in operating efficiency, it should correct the malfunction of 3-way valve and expansion valve and the mistake of control values for schedule program and increase cooling tower capacity. In order to improve piping line, it needs bypass brine line off refrigerator, separation of chilled water line with Ice Slurry system at day and night time and speed control of chilled and warm water pumps. This study does require the more studies on improving difficulty of increasing cooling load with Ice on Coil system, waterproofing with Ice Ball system, COP drop during the night time with Ice Lens, low operating temperature during the day time with Ice Slurry and increasing of Power loss due to hot gas de-icing with Ice Harvest in the future.

The objective of performing this study is to develop low emission condensing gas boiler. To reduce NOx and CO, three reasonable distances between burner and heat exchanger were decided through the experiments of model plane burner. Three burners with different diameter were made and then emission characteristics were examined. The optimum burner geometry was determined from flame stability, pollutant emission characteristics and applicability to the practical boiler system. In the domain of equivalence ratio 0.68~0.85, turn-down ratio of the burner designed by this research was extended to a wider range of 5 : 1. Thermal efficiency of the boiler developed by this study reached to 97% (LHV basis) of heating water efficiency at heating load of 20,000 kcal/hr when fueled by both of LNG or LPG. Emission (=0%, wet basis) of NOx and CO concentration was 26 ppm and 85 ppm when fueled by LNG, 41 ppm and 113 ppm when fueled by LPG respectively.

One of the most serious concern in nuclear power plant piping maintenance is thickness reduction due to flow-accelerated corrosion (FAC). Since the FAC occurs under specific conditions of pH, dissolved oxygen, temperature, flow velocity, steam quality of the fluid and materials and geometry of the piping, a systematic approach is required for managing the FAC problem. In this study, construction of a secondary piping database, analyzing the FAC rate using the database and predicting the residual life was performed for a domestic CANDU nuclear power plant. Also FAC mechanism and factors affecting FAC were reviewed. By showing a case study on analysis for a pipe line between a separator and a flash tank, a procedure for managing FAC problem is suggested. The procedure proposed in this paper can be widely applied to the secondary piping of other domestic nuclear polder plants.

In this paper, incompressible and compressible flow characteristics around the butterfly valve have been investigated. In order to simplify the problem, a flat disk valve with various valve disk angles and pressure ratios is considered in the present calculations. It was found that as the disk angle increases, the stagnation point on the front surface of the disk moves to the center of the surface and the inflow velocity decreases. The maximum flow velocity occurs at the downstream of throat because of the formation of vents contracta. As the pressure ratio decreases, compressibility effects increase and the jet formed between the throttle body wall and the disk edge becomes supersonic. This flow also builds up as a shock cell structure. The increase of disk angle and pressure ratio makes the mass flow at the inlet decrease, while the increase of disk angle and the decrease of pressure ratio make the pressure loss coefficient increase.

Carbon accounting is a key issue in the discussions on global warming/COmitigation. This paper applies both the IPCC Approach and the NEAT (Non-Energy use Emission Accounting Tables) model, a bottom-up approach, to estimate the potential CO emissions (carbon storage) originating from the non-energy use as to assess the actual CO emissions (carbon release) from the use of fossil fuels in Korea. The current Korean carbon accounting seems to overestimate the potential CO emissions and with it to underestimate the actual CO emissions. The estimation shows that the potential CO emissions calculated according to the IPCC Approach are lower than those calculated using the NEAT model. This is because the IPCC default storage fraction for naphtha seems to be low for the Korean petrochemical production structure, on the one hand and because the IPCC Approach does not consider the trade with short life petrochemical products, on the other hand. This paper shows that a bottom-up approach like the NEAT model can contribute to overcome some of limitations of the IPCC guidelines, especially by considering the international trade with short life petrochemical products and by estimating the storage fractions of fossil fuels used as feedstocks for the country in consideration. This paper emphasizes the importance of accurate energy statistics for carbon accounting.

This paper presents a new method for the evaluation of avoided generation costs. Unlike conventional load decrement method, it exactly considers forced outage rate and economic loading order of IPPs (Independent Power Producers). Therefore we can provide exact generation avoided costs of IPPs by the developed method. Because probabilistic simulation is conducted in this method, effects on the costs of IPPs are exactly considered. Also we suggest an allocation method of avoided generation costs by participation factor. In the case studies we have shown avoided generation costs considering loading order and forced out-age rate by using this method.

The vertically integrated power industry was divided into six generation companies and one market operator, where electricity trading was launched at power exchange. In this environment, the profits of each generation companies are guaranteed according to utilizing strategies of their own generation equipments. This paper presents on generator maintenance scheduling and efficient bidding strategies for generation equipments through the calculation of the contract and the application of each generator cost function based on the past demand forecasting error and market operating data.

The carbon-in-ash system for simultaneously monitoring the unburned carbon in fly ash produced in a coal-fired power plan is designed and evaluated using the domestic fly ash produced in the coal-fired power plant. Real time monitoring is very important to control the combustion of the boiler in the coal-fired power plant and the purification system for fly ash recycling. The carbon-in-ash system based on the capacitance measurement consists of a LCR meter, a duct collector and an electrode cell. The capacitance of fly ash increases linearly with increasing fly ash carbon contents. The water content in fly ash plays an important role on the ash capacitance. The empirical equation for predicting the content of unburned carbon in fly ash produced in the domestic Boryung, Hadong and Samchenpo coal-fired power plants can be derived in the range of carbon content 0-20%.

In this study, a numerical method for fuel droplet evaporation in cylinder of S.I. engine is presented. This study was newly defined non-dimensional critical droplet lifetime and modeled heating and evaporation processes of fuel droplet during intake and compression stroke of gasoline engine. The simulation results show that simultaneous increase of gas temperature and pressure in compression stroke seems to have compensative effect on droplet gasification rate. The environment variations in cylinder have little effect on the fuel droplet gasification process. The droplet size for full evaporation at the end of compression stroke can be estimated using this program.